Andrew Groover celebrates the complexity of trees, and makes it his life’s work to unlock how they adapt to their environments. It’s knowledge that’s critical for the U.S. Forest Service research geneticist — he works in California, where concerns about climate change have grown as wildfires there have increased in frequency and intensity.

A practical problem for Groover, who is a University of California, Davis, adjunct professor of plant biology, is efficient access to the variety of trees he studies. His research requires a ready supply of species diversity, a tall order without laborious travel. But in 2012 his search for the perfect resource brought him to the Arnold Arboretum of Harvard University — a 281-acre living museum holding more than 2,100 woody plant species from around the world.

“Trees are fascinating for biology and research, but one of the greatest challenges in this research is finding trees tractable for study,” Groover said. “If you have a list of a dozen or two different species, where do you get all those? The Arnold Arboretum has all of the species we would ever want to look at, and then some.”

The Arboretum also contains one of the most extensive collections of Asian trees in the world, which Groover said is advantageous to his research. Typically a researcher has to travel to various locations throughout the world, determine whether the trees are on public or private property, obtain permission to study and transport samples, overcome language and other barriers, and potentially return to the same site later to complete research, which can be challenging.

“The Arnold Arboretum plays a crucial role in research and science and educating the public, connecting them with trees and forests. But it’s also a living laboratory and repository of hard-to-source species for research and is renowned for its collection of Asian disjuncts,” he said. “We can actually study these species pairs found in both Asia and the U.S. directly in the Arboretum. We didn’t need to go anywhere else.”

Director of the Arnold Arboretum and Arnold Professor of Organismic and Evolutionary Biology William (Ned) Friedman emphasized the extraordinary efforts that go into creating such a high-impact research destination.

“Importantly, beyond the more than 16,000 accessioned woody plants at the Arnold Arboretum, we have a staff of world-class horticulturists, propagators, IT professionals, curators, and archivists, all of whom are devoted to ensuring that the living collections are what I call a ‘working collection’ of plants,” he said. “The plants of the Arboretum may look great in flower, or at the peak of fall colors, but these plants are here primarily to be studied by scholars at Harvard and from around the world. In 2018 alone, there were 79 different research projects using the living collections and landscape of the Arnold Arboretum.”

Groover’s work with the Arboretum became a long-term collaboration. In 2014 he won a Sargent fellowship, and, working with Arboretum scientists, collected small samples of genetic material from specific Arboretum trees and propagated them in his own laboratory greenhouses. In 2015 Groover, with Friedman, organized the 35th New Phytologist Symposium held at the Arboretum. He has also given several research talks there, most recently in December on genomic approaches to understanding the development and evolution of forest trees.

“When the Weld Hill Research Building was completed [in 2011], many of us in the research community saw that as a real commitment holding great possibilities for expanding into new areas of research,” he said. “We could not only access a broad range of species all in one location, we had a physical facility for research activities.”

Groover’s work investigates genetic regulation of wood formation — the triggers of gene expression within the wood — which is driven by environment, including light, temperature, wind, water, gravity, even insects and disease. Studying diverse tree species helps him identify the genetic basis of how different species modify their growth and adapt to different environmental conditions.

“Trees in general are very responsive to the environment, and trees can actually make adjustments in their wood anatomy to suit the environment,” Groover said. “One thing that is really interesting about trees is that they are perennial and live to decades or even thousands of years in the same place, and they have to be able to cope with all of the variation.”